A conventional leadlight control apparatus for a vehicle calculates a direction (i.e., control direction) in which a headlight is forced to irradiate a beam in a plurality of methods as disclosed in JP 2002-225617A, for example. This control apparatus properly switch a method of calculating a control direction of headlight irradiation based upon a steering angle of a driver and a method of calculating a control direction of headlight irradiation based upon the direction of a guide route by a navigation system for use.
However, at the time of switching the calculation methods for the control direction of headlight irradiation, a rapid change in the control direction possibly occurs. For example, a method of calculating the control direction in headlight irradiation based upon the direction of the guide route in the navigation system is switched to a method of calculating the control direction of headlight irradiation based upon a steering angle of a vehicle. This calculation method switching possibly results in that the control directions calculated by the two methods are different from each other at a moment when one of two methods to the other is switched, caused by that information of the navigation system in regard to the shape of a road ahead of a vehicle is not accurate or the like. Difference in control direction of headlight irradiation in the two methods possibly leads to a rapid change in the control direction at the time of the calculation method switching.
When the control direction thus rapidly changes at the time of switching the two control directions, the rapid change in irradiation direction of a headlight results in poor forward visibility of a driver.